1. Field of the Invention
The present invention relates to electronic equipment, and more particularly to electronic equipment having a plurality of key input units such as an electronic desk-top calculator.
2. Description of the Prior Art
In prior art electronic equipment of this type, a key input unit comprises movable contacts formed by conductive rubber and key tops, and a printed circuit board arranged on the movable contacts. A separate display unit and a separate unit for accommodating a power supply such as batteries are held by separate members.
Because of such construction, the number of parts is large and the number of assembling steps is also large and associated management requirements such as parts management are complex. As a result, the cost of the equipment increases.
A thin desk-top calculator has been recently marketed but it is weak in strength because of thin structure.
In a key input unit of the prior art desk-top calculator, stationary contacts for key input are formed on a printed circuit board in a predetermined pattern. Movable contacts made of silicone conductive rubber are vertically movably held at positions facing the pattern, and separate key tops are arranged on the movable contacts.
With such a structure, the conductive rubber of the movable contacts is separate from a frame and it must be mounted at a predetermined position in an assembling step. Further, a plurality of separate key tops must be fitted to key top holes formed in the frame. If the frame is upset or vibrated during the assembling step, the key tops are scattered here and there. Thus, the number of steps increases and the handling is very troublesome.
When a thin desk-top calculator which is convenient to carry is desired, there is a limit to the thickness of the silicone rubber. It is difficult to provide a click feeling with a short key stroke and this may cause misoperation.